NSK's new HPS series spherical roller bearing (SRB) is claimed to offer twice the running life of conventional bearings of equivalent size, as well as lifting the maximum limiting running speed by up to 20%. Compared with other types of bearing, SRBs have a high load capacity and self-aligning feature that allows for some misalignment of the axis of rotation.
Key to the self-aligning property of NSK's new SRB is the spherical profile of the bearing rollers acting in the bearing inner and outer ring raceways. But this configuration can produce slippage at the contact points between raceways and rollers, causing premature wear. NSK has overcome the problem to a great extent, controlling the motion of the rotating rollers by applying a special surface treatment to the outer ring.
In addition, the company has applied a special nitriding surface treatment to the HPS series pressed steel cage, which has significantly reduced wear under harsh operating conditions. NSK's nitiriding treatment forms a finer, harder surface with more uniform hardness compared with more conventional methods, and the dimensional accuracy of the cage is maintained during this high temperature process. Initially, NSK plans to make 42 sizes available, with outside diameters ranging from 80 to 260mm.